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Home >> Volvo >> 1993 >> 850 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Trouble Code Testing >> Ignition System Trouble Code Diagnosis >> 1-3-1 (VSS Signal Absent) & 2-1-4 (VSS Signal Intermittent)

1-3-1 (VSS Signal Absent) & 2-1-4 (VSS Signal Intermittent)

  1. Connect measuring unit to ignition ECU. See MEASURING UNIT  under SELF-DIAGNOSTIC SYSTEM. To check VSS signal, connect voltmeter between measuring unit terminals No. 1 and 2. Operate starter motor. Voltmeter should indicate 300-400 millivolts with ignition switch in START position and about one volt with engine running.
  2. If voltage is not present, turn ignition off. Connect an ohmmeter between measuring unit terminals No. 1 and 2. Resistance should be 200-400 ohms, depending on temperature. Connect ohmmeter between measuring unit terminals No. 2 and 20. About zero ohms should be present.
  3. Disconnect Camshaft Position (CMP) sensor connector to prevent it from setting code. Use diagnostic test mode No. 2 and recheck sensor signal. See DIAGNOSTIC TEST MODE NO. 2 under SELF-DIAGNOSTICS  . Operate starter motor. Code 1-4-1 should be displayed (vehicle speed sensor). If code is not displayed, repeat test using new ignition ECU.
  4. If no electrical fault is found, ensure carrier plate is not damaged or distorted. This problem, which applies primarily to A/T vehicles, can prevent engine from starting and set a code.
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